Various types of closures have been designed to provide a visual indication to the end consumer that the contents of the container have remained sealed and have not been tampered with. In the liquor industry, paper seals in the form of excise stamps are often applied over a screw-on cap so that the paper seal must be broken to gain access to the container. In the wine industry, it is common to provide a wrapping of foil about the neck and mouth of a bottle or in some instances, the use of a plastic oversleeve provides this visual indication that the contents are as originally packaged. The market has widely accepted the concept of providing a guarantee seal however, this often requires an additional packaging step leading to higher production costs.
To alleviate this problem, several types of metal closures such as that disclosed in U.S. Pat. No. 2,367,317 which issued to J. W. Thomas, Jan. 16th, 1945, have been proposed which have a screw on cap portion and a depending pilferproof band which is secured to the cap by a number of severable bridges. With that system the cap is normally a sleeved blank made of aluminum and during application to a threaded glass bottle, the metal sleeve is crimped in position to snugly adhere to the neck portion of the bottle. Closures of this type have gained wide acceptance in the beverage industry, particularly, the liquor and softdrink sector, however, they require sophisticated capping equipment.
A number of designs have been proposed to manufacture a pilferproof closure of the type having a cap and a depending pilferproof band which is made of a plastic material with the pilferproof band adapted to snap over the shoulder provided on a container. In contrast to the metal closures described above, the caps are injection molded prior to container application with the threads and the undercuts for maintaining the band on a container. The closure is subsequently screwed on the neck of a container without further production steps. An example of this type of closure is U.S. Pat. No. 3,708,041 which issued to Birch, Jan. 8th, 1974. However, caps of this design have proven unsatisfactory due to their unrealibility in the band separating from the cap during application to a container. For example, with glass containers, a substantial tolerance variation can occur. Therefore, closures of this type have not proven to be reliable in providing a visual indication that the contents of the container have not been tampered with. When the tolerance on the shoulder provided on a container is near its maximum, application of the closure results in a fairly high frictional force as it is attempted to force the band over the shoulder with the result that the interconnecting bridges may all be severed or a number of them severed during the capping operation. Further problems such as buckling of the band above the shoulder or splitting of the band may also result.
The structure of U.S. Pat. No. 4,033,472 which was assigned to Albert Obrist, overcomes the above problems by providing a plastic closure which is screwed over the mouth of a glass container with the pilferproof band subsequently heated and deformed beneath a shoulder on the container. Such a system overcomes the problems of buckling of the pilferproof band and/or severance of the interconnecting bridges during application. It requires, however, an additional process step which is difficult to control. In addition, the deforming of the band beneath the container shoulder can result in a mis-shapened, distorted band which is not attractive from a marketing standpoint.
The present invention seeks to mitigate a number of problems of the prior disclosures and devices by providing a plastic closure which is simple to apply during the capping operation while maintaining its pilferproof feature.